2 Answers
2

These are the kinds of touchscreens used on older devices that can only accept a single point of input. They work by returning a resistance of x, and of y, to determine the position on the screen.

Using one of these would require significantly less code, and processing power then using vision processing. The ball could simple sit on this plate, and as it rolls around, you will be able to determine the exact XY coordinate of the ball.

By doing a simple Google search and find hundreds, of all sizes, with or without an LCD attached.

Here is an example of what I imagine you are trying to do. The position of this ball is measured by a Resistive touch panel. YouTube Link

Image processing is a valid solution to the ball on a plate problem. It will give you a very accurate estimate of the position of the ball. You should be able to do this with a raspberry pi. With regard to sensors, any cheap webcam should do the trick.

The vision processing involved will be trivial if you are familiar with python or c++.